This invention relates to the water shield associated with a plasma arc cutting apparatus and, more specifically, to the water shield delivery ring mounting arrangement.
It is customary to mount a water shield ring directly to the cutting torch of a plasma arc cutting apparatus which is used to cut a steel plate workpiece. During the cutting process, cooling water is delivered through a hose to the shield ring and therefrom onto the workpiece in the immediate vicinity of the cutting area. The delivered water reduces smoke and noise generated during the cutting process, and further assists in the prevention of heat distortion of the workpiece.
The customary mounting arrangement of the water shield ring has been postulated to precipitate the premature buildup of carbon along the cutting torch of the plasma arc cutter. This buildup results in distortion of the associated electrode tip and associated components, and as a result thereof, an improper bevel cut. Further, carbon buildup facilitates shorting out of the height sensing system of the plasma arc cutter, resulting in an improper height setting of the torch during the cutting process. A still further problem results from repeated raising of the torch. When the cutting torch is raised to allow the substitution of workpieces, the weight of the associated hose on the shield ring causes the cutting torch to be subjected to a torsional load resulting in bending of the cutting torch. As a result of torch bending, the cut produced by the cutting torch is beveled. The cited problems result in substantial machine downtime and a significant amount of improperly cut workpieces.